Automatic telephone system



Aug. 9, 1932. J. E. GARDNER AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet l *Nm SN 6% Aug. 9, 1932.

J. E. GARDNER AUTOMATI C TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet 2 Erg YM Aug. 9, 1932.A .1. E. GARDNER' 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 21. 192'?r 18 Sheets-Sheet 5 Aug. v9, 1932. J. E. GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 21. 1927 18 Sheets-Sheet 4 @y @www M Caf/a Aug.v 9, 1932. J. E. GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM A original Filed Nov. 21. 1927 18 'Sheets-sheet 5 55] frzzrmaf Jm' E.' Gardner Aug- 9, 1932 J. E. GARDNER .Y 1,870,621

AUTOMATI C TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet 6 Aug- 9 1932- J. E. GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet 7 FiF-YV J. E. GARDNER AUTOMATIC TELEPHONE SYSTEM Aug. 9, 1932.

Original Filed Nov. 21.1927 18 heets-Sheet 8 @zii Aug- 9, 1932 J. E. GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet 9 Aug. 9, 1932. .1. E. GARDNER 1,870,521

AUTOMATIC TELEPHONE SYSTEM original Filed Nov. 21, 1927 18 sheets-snaai 1o Aug. 9, 1932.

.L E. GARDNER AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet 1l Ss QS z o S @di im mw mg @i In A11g 9 1932 J. E. GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 21. 1927 18 Sheets-Sheet 12 iJiffy/z.

Aug. 9, 1932. J. E. GARDNER AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l, 1927 la Sheets-Sheet 13 m. NQS N www@ @am A ug. 9, 1932. J. E GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 21, 1927 18 Sheets-Sheet `14 A1199, 1932- J. E. GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet 15 Allg- 9, 1932- J. E. GARDNER 1,870,621

AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l, 1927 18 Sheets-Sheet 16 Aug. 9, 1932. J. E. GARDNER AUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 2l. 1927 18 Sheets-Sheet 17 Aug. 9, 1932.

J. E. GARDNER AUTOMATIC TELEPHONE SYSTEM original 11.1.1811 Nov. 21. 1927 18 sheets-sheet 18 John E Gardner Patented Aug. 9, 1932 STATES PATENT OFFICE JOHN E. GARDNER, OF CLARENDON HILLS, ILLINOIS AUTOMATIC TELEPHONE SYSTEM Application led November 21, 152'?, Serial No. 234,752. Renewed January 14, 1932.

The present invention relates in general cient combination to completeconnections beto automatic telephone systems. tween calling and called lines.

One of the objects of my invention is to A further object is to provide circuit and provide a highly novel and eiiicient trunking selecting mechanism whereby a connection system. may be completed between a calling and a 5 Another object is to entirely eliminate the called line substantially instantaneously.

trunk hunting time that is now required for A still further object is to provide imthe automatic selection of an idle trunk at proved translating and controlling mechathe end of each digit or stage of directively nisni whereby the foregoing results may be 1U controlled selection. l obtained in a highly complex metropolitan Another object is to pre-select idle trunks exchange area with an ultimate capacity for extending between the various numerical connections between any two of ten million groups so that a call may be projected from a lines. called line completely over pre-selected idle Still another object is to provide improved i', trunks, apparatus and circuits so that the controlling 55 Another object is to eliminate all the highmechanism thus mentioned may be properly ly complex apparatus that has formerly been directed from a telephone subscribers subrequired to complete connections within an station. automatic exchange area comprising many There are other objects of my invention o offices and to make use of very simple equipwhich, together with the foregoing' will be 70 ment from a. mechanical standpomt. described in the detailed specification which Another object is to use a single type of is to follow, taken in conjunction with the mechanism throughout the system for estabaccompanying drawings. lishing connections between calling and Standard telephone practice of the present 25 called subscribers telephone lines. dav as known to applicant divides the metro- 75 A further object is to provide a novel and politan area into a number of automatic exhighly efficient inter-office trunking system changes7 if an automatic system is installed, whereby connections may be completed beinto ten thousand line oflices. In large metrotween various oces in a multi-oiiice area politan areas the number of these exchanges u U and between subscribers in the various exapproaches one hundred and in many inim changes by the use of a very small amount stance go as highly as several hundred. Of of equipment in a highly ei'cient manner. course, where there are several hundred ex- A further objectis to reduce the amount of changes, a' considerable number of these will equipment necessary to establish a connecbe smaller oiices than ten thousand lines, f 35 'tion between calling and called telephone being created as a result of the distribution of 8J lines to a minimum. subscribers from economic studies to deter- A further object is to render the more cominine the best procedure. In other instances plex circuts and equipment common to a conditions of this nature are directly attribplurality of connections and associated with utable to the manual telephone exchange sysw a. call only during the period that the functem, which the automatic is to replace.

tioning of this more complex apparatus is Vherever there arev aV large number of necessary. oflices it is necessary in present practice to A further object is to simultaneously prouse the first three digits of the subscribers ject a calling line over two paths, one of number to locate or identify the oice and to 4,3' which might be termed a setting or selecting employ the remaining four digits to select path and the ether a talking path, releasing the wanted subscribers line in the office. It the setting path as soon as the talking path is theoretically possible, of course, to select as is established. many as one hundred exchanges by two digits A further object is to provide selecting using the decimal system of numbering. Ac- Jo' mechanism of the relay type in a highly ei'iitually, however, the exigencies of the selecting apparatus cuts this down to 90. In addition it has become desirable to continue the manual practice of designating oices by names instead of numbers, it having been found that the subscribers can remember telephone numbers designated in thismanner with a great deal more facility. y In viewkof the foregoing 'it is entirely iimpossible to vdit-- ferentiate 'between the various exchanges of a metropolitan area until the third digit 'has been dialed or otherwise :transmitted lections of this kind are usually handled by providing a storing device wlfrihiscomrected to the subscribers line upon the initiation of a call and serves to registerth'e ldigits-of the wanted subscribers number .and then vcontrol the establishment .of :the connection.

This controlling .device which 4.goes vunder the mameV of director .or translator or .sender is used in all .automatic .metropolitan Vexchange areas.

Heretofore in the engineering .of .large multi-oilice areas .and 'in .designingfan `automatic telephonesystem -to iitsuchan area, the problem fhas been considered as a whole. As :a

result yof this conception .su'icient selecting apparatus had to be .provided .for connecting any subscriber in the exchange area to vany other subscriber in the exchangearea.;v that iis,

. this was the normal selecting route necessitating a certaiunumber ofstages ofrselection and each call had to ,go through .the'required number of stages. vThe translator, sender .or director eliminated certain of @these stages Iin certain special instances, such as .localoice calls through .the number of stages 'of selection ior connecting 'the subscribers together remained lthe same.

The present invention contemplates that all the selecting a y,paratus Ythat .is necessary and the number o selections necessary is :determinedthesize of -the oiliceorumt.; that is, 'the only selecting apparatus that .isnecessary inany exchange is that which'is required to connect any subscriber in that exchange to any other subscriber therein, lin addition, of course, 'to -being able to extend any :subscriber?s line in the exchange \tofinter.ollice trunks as willbe explained. AB y -this method of treat- 1.5 ment each exchange is considered as a .unit

and ythe metropolitan exchange area fis `considered as an assembly olf these units.L

NoW considering a single unit of ten thousand lines, su'li'cient apparatus is .provided to complete a connection between any 'two of said lines. In addition, the selecting mechanism .is capable of selecting the trunk lines that extend from it to certain other ofices. The number of these inter-oice 'trunks and *'-Y the particular-offices that are connected together by trunk lines :depend .upon `the exigencies of traic and the trunkiug -eiciency and economy. That is to. say, the inter-ofiice trunking maybe planned entirely -indepenc'lent lof the localtraiiic in any oilice and 'inaccordance with the best plan that may be arrived at basedon traine studies and geographical location so as to secure the maximum efficiency of inter-oiiice trunking. The

incoming trunks into any office come in on What might be termed iirst selectors, that is, they come in through the local trunking system in the same mannergasa localcall. Since they start at this point they may be handled identically the same as a local call. If the .connection is to be tandemed through this ofice itis extended to another office in identilcally the same manner.

Bythis plan great economy is secured both in the amount of selecting appara-tus required and inthe number of inter-ofiicc trunks necessary. 'This result ,is obtained withoutsacriicing any of the .features .of the .usual automatic metropolitan .exchange system, in laddition to providing many novel operating features.y f

Many .attempts have .been made heretofore to increase the speed of establishing a connection between a callinganda called line .in automatic telephone systems. One of ythellimiting .factors in former automatic ytelephone systemshas been vthe speedat which impulses could be .sent `.to directively control the central Vioiice switching equipment. Another limiting factoris the speed at which it is possible .to yoperate and control .the .mechanical devices .that are used to complete theselecton at the` central office. Another factor that limits thespeed of establishing connection is the .trunk hunting time required at the end of each directively controlled stage of selection.

-One ofthe methods that :has'been employed heretofore to increase thespeed of selection is to employ .a :relay selecting system. However, relay .selecting systems 4are Avimpractical except in exchanges of a vsmall number of lines .from to `100 `on account of the prohibitive cost. In addition, the controlling mechanism which Vcontrols theselectingmcchanism from lthe subscribers sub-station will not positively` control the selecting apparatus at a speed greater Athan Q0 impulsesa second.

.even though relay selecting apparatus is employed. f

'Other attempts have been made to preselect trunks, but it has been found impractical to do .this except intwo Lor three places, namely, .primary line switch pre-selection, secondary line switch pre-selection and in pre-selecting idle ,trunks 4between oilices. This last e'ort involves considerable-apparatus .and can only Vbe justifiedby va saving in the inter-oiice trunks.

The present invention employs the 'simplest .kind of mechanical apparatus which .is nothing more than relays and combines them in a highly novel trunking system so that all the trunks from .the calling to the called lines are pre-selected and in order to make the se- 

